The Poison Review

A RETROSPECTIVE EVALUATION OF SHORTENED-DURATION ORAL N-ACETYLCYSTEINE FOR THE TREATMENT OF ACETAMINOPHEN POISONING Betten DP et al. J Med Toxicol 2009 Dec;5:183-190.

The tortuous argument this paper presents can be deduced from the hair-splitting language used in the abstract’s conclusion: “Treatment with shortened-course oral NAC [N-acetylcysteine] in patients meeting criteria for early discontinuation may be an effective treatment option in a sizeable proportion of individuals with potentially toxic acetaminophen ingestions”.  Well, anything may be effective.  Is it or isn’t it?  And if such a shortened-course may be effective in a “sizeable proportion”, how do we determine exactly which patients may comprise this population?

I actually agree with the authors.  Their short-course protocol for treating acute acetaminophen (APAP) poisoning calls for administering NAC for a minimum of 20-36 hours, and discontinuing treatment at that time if serum APAP levels are < 10 mcg/ml, AST and ALT are both < 60 IU, and INR < 1.3.  Evidence for this approach in acute toxicity has been published in previous studies. This retrospective review looks at applying a similar protocol to patients with chronic ingestion (> 1 hour) and those in whom time and/or pattern of ingestion is not known.  I’m convinced that this is reasonable and is — based on published research and clinical experience — safe. Unfortunately, this retrospective review has so much missing information and required so many assumptions, that it does not advance our understanding of the problem.